The effect of lignin degradation products on the generation of pseudo-lignin during dilute acid pretreatment

• Published in: Industrial crops and products Vol. 146; p. 112205
• Main Authors: He, Juan, Huang, Caoxing, Lai, Chenhuan, Huang, Chen, Li, Mi, Pu, Yunqiao, Ragauskas, Arthur J., Yong, Qiang
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 01-04-2020; Elsevier
• Subjects: Acid-pretreatment; BASIC BIOLOGICAL SCIENCES; Lignin; Phenolic compound; Pseudo-lignin; Lignin; Acid-pretreatment; Phenolic compound; Pseudo-lignin
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2020.112205

•Glucose and xylose go through different pathways to form pseudo-lignin.•Lignin phenolic compounds changed the composition of hydrolyzate.•Pseudo-lignin possess different chemical structures in the presence of lignin phenolic compounds
Pseudo-lignin is an insoluble material that tends to deposit on acidic pretreated fiber surface and negatively impacts the biological conversion of biomass to valued added products. Employing a laboratory generated acidic hydrolysate solution from dilute acid pretreatment of bamboo residues, we sought to seek an improved understanding of pseudo-lignin formation from fragmented carbohydrates. In addition, we also performed experiments to investigate how lignin model compounds interact with carbohydrates en route to pseudo-lignin’s formation. The yields of pseudo-lignin generated from xylose (CXPL) were higher than those generated from glucose (CGPL). Gas chromatography-Mass spectrometry and Foloin-Ciocalteau analysis suggested that there were more aromatic compounds in hydrolyzate during CGPL’s formation. The presence of lignin phenolic model compounds had both a positive and negative effect upon quantitative yields of pseudo-lignin. Gel permeation chromatography and NMR analysis (31P and 2D-HSQC NMR) of the pseudo-lignin samples generated in the presence and absence of 4-hydroxybenzoic acid (4-HA), employed as a lignin model compound, revealed drastic differences in molecular weight, changes in hydroxyl group content, and hydrocarbon bonds, suggesting significant differences in the pseudo-lignin reaction pathways when certain lignin model compounds are present. Our findings demonstrate the effects of both hemicellulose carbohydrate makeup and lignin model compound impact on the formation of pseudo-lignin and its chemical properties, suggesting a potential way to minimize pseudo-lignin formation.